The present invention relates to an improved method for the manufacture of textile products of the xe2x80x9clapped/bondedxe2x80x9d type directly from fibres and/or from filaments.
The invention also relates to an apparatus for carrying out the method and to the products obtained by means of the said method.
So-called xe2x80x9clapped/bondedxe2x80x9d products are products which are produced from a textile lap, preferably from a lap already consisting of threads, or, if appropriate, from a fibrous lap, which is subjected to a succession of foldings for the purpose of forming folds which may be likened, in the direction of advance of the lap, to loops. This folded lap is subsequently simply fixed to a support by adhesive bonding. A product is thus obtained, in which the threads and/or fibres do not pass through the support, in contrast to tufted products which take the form of a succession of loops passing through the support.
There are, at the present time, essentially two large families of methods intended for producing textile products of the xe2x80x9clapped/bondedxe2x80x9d type.
The first family is the best known and comprises the methods employing a machine with arms, to which blades are fastened. A lap of threads is pushed by these blades successively onto a first backboard, then onto a second backboard which is parallel to the first, in order to form a succession of loops by folding. These loops are subsequently fixed to a support which is preferably coated beforehand with a glue, such as a polyvinylchloride paste, and onto which the loops will be deposited, the assembly thus formed by the support and the fixed loops being subsequently subjected to thermal treatment, for example passage through an infrared furnace.
According to another embodiment, the loops may be held between two supports, before a hot-melt adhesive passes through the said supports in order to impregnate the bases of the loops.
At all events, whether by fixing of the PVC type or of the hot-melt type, the product obtained either has a looped appearance resembling a looped tufted product or is of the xe2x80x9csandwichxe2x80x9d type, consisting of loops trapped between two supports which may be subsequently split longitudinally in order to obtain two products of the pile fabric type.
Another alternative involves proposing the use of tensioned cables to replace the blades mentioned above.
According to the second large family of methods, successive folds are formed by means of a rotary system, by pushing the threads and/or fibres of the lap successively into protuberances present on a grooved cylinder. The folds are made under the action of a folding member, such as a blade or a roller, which are themselves grooved. Subsequently, a support, preferably coated beforehand with glue, is arranged on the succession of loops obtained by folding. If appropriate, the assembly consisting of the support and of the fixed loops is subjected to thermal treatment before these are removed from the grooved cylinder.
It is expedient to note that all these methods have the following disadvantages:
their production speed remains relatively low. As an example, 120 strokes per minutes is already a relatively high speed for a system with arms, as described above, because of the complexity of the movement generated by the cam members;
the quantity of adhesive necessary for fixing the loops to the support remains large, and therefore the products obtained are still relatively too costly;
the range of products of the xe2x80x9clapped/bondedxe2x80x9d type which can be produced is relatively limited.
On the other hand, the Applicant developed a technique for producing textile products directly from fibres and/or filaments, which is called the xe2x80x9cverticalization techniquexe2x80x9d.
This technique is described in the patent application published under number WO91/00382, and makes it possible to produce products, such as floor and/or wall coverings of the moquette type, directly from fibres and/or filaments travelling in the form of a web.
The technique described involves subjecting the fibres and/or filaments to xe2x80x9ctransverse loopingxe2x80x9d accompanied by xe2x80x9cdrawingxe2x80x9d and obtaining an accumulation of fibres and/or filaments in the form of a crimped xe2x80x9cpseudo-yarnxe2x80x9d, in which the fibres and/or filaments are parallelized. This step is referred to, in general terms, as the xe2x80x9c(pre) looping stepxe2x80x9d and must not be likened to folding.
This document describes that transverse looping accompanied by drawing is carried out, for each individual fibre or filament, by means of rotary elements or looping discs which are spaced and arranged on a shaft transverse to the direction of advance of the web and between which looping fingers are arranged. Each fibre or filament is, in principle, thereby involved in at least one looping. A non-twisted pseudo-yarn is thus formed, obtained by the accumulation of the various exactly parallelized elementary fibres and/or filaments, the said accumulation having a looped form.
The accumulation of the parallelized fibres and/or filaments in the form of the pseudo-yarn takes place either in the open needle eye, as described in detail in the Applicant""s publication WO91/00382, or in notches provided in transfer elements, as described in the document WO96/10667, also of the Applicant.
With the aid of these transport members consisting either of the needles or of the transfer elements, the pseudo-yarn is subsequently transported, in the form of transverse rows of loops, towards a support to which the loops are fixed.
In the publication WO91/00382, fixing is carried out by passing the needles through this support for the purpose of producing, more specifically, a floor covering of the tufted type.
This method was made even better by proposing the improvements described in European Patent Application EP 95870093.2, in which the method described in the publication WO91/00382 is combined with the use of a lap drawframe, as described in the document EP-A 0,520,911. Moreover, it is proposed to double the looping elements by adding a step called the xe2x80x9ccrimping stepxe2x80x9d, so as to limit the forces on the shafts which arise as a result of the use of a web coming from a conventional lapper.
In this case, there are at least two separate assemblies of elements: the first assembly is intended for carrying out a crimping step by means of an apparatus consisting of the interpenetration of a first set of crimping discs with a first set of crimping fingers, whilst the second assembly is intended for carrying out the conventional subsequent step, called the prelooping step, by means of an apparatus consisting of the interpenetration of a second set of discs, called looping discs, with a second set of fingers, called looping fingers, this second assembly being arranged downstream of the crimping device in relation to the direction of advance of the web. The gauge of the crimping apparatus is a multiple of the gauge of the prelooping apparatus.
The products proposed in this document are essentially in the form of tufted products.
At this stage, it has been possible for this verticalization technique actually to achieve industrial use. In fact, it has been possible to control the levels of forces and torques even in the case of very large working widths (for example, greater than 4 meters).
Nevertheless, although this method can be fully put into practice on an industrial scale, it must be accepted that its productivity still remains limited. This is essentially due to the presence of transport members which execute an alternating movement and which are either in the form of needles or else in the form of transfer elements, as described in the document WO96/10667.
In fact, the production speed, which may be expressed as the product of the advance of the substrate per stroke (in mm) and the beating speed of the needles (in strokes per minute) reaches an order of magnitude of 1.5 to 4.5 m/min, this being perfectly acceptable for producing tufted products, but still remaining too low for production comparable to a needling line, the production speed of which may reach an order of 15 m/min.
Moreover, for obvious reasons of overall size due to the presence of needles or even of transfer elements between the looping discs, it is difficult for the gauge of a so-called verticalization apparatus to be below {fraction (1/10)}th of an inch, that is to say 2.54 mm, unless it becomes possible to produce highly accurate and therefore relatively costly members, thus depriving the so-called verticalization method of the possibility of producing products inexpensively.
On the other hand, a trend in the tastes of consumers towards fine-gauge products may be seen. These products are those where the advance per stroke and consequently productivity, too, are the lowest. This is a measure of the usefulness of a method in which very fine gauges would be easy to produce, without the production speed having to be limited.
The present invention aims to provide a solution to the existing limitations, more particularly as regards productivity, in the methods employed in the so-called verticalization technique, as is described in the documents WO91/00382 and WO96/10667.
The present invention aims, more particularly, to make it possible to produce so-called xe2x80x9clapped/bondedxe2x80x9d products which may have an appearance close to those known in the prior art, whilst allowing very high productivity when the method is implemented.
The present invention aims, in addition, to make it possible to produce products of the xe2x80x9clapped/bondedxe2x80x9d type having a fine gauge, that is to say a gauge below {fraction (1/10)}th of an inch.
Moreover, the present invention aims to make it possible to produce new products which have been impossible to produce at the present time, using the technique described as such in the Applicant""s prior publications and, more particularly, in the publications WO91/00382 and WO96/10667.
The present invention relates to a method for producing a textile product of the xe2x80x9clapped/bondedxe2x80x9d type from fibres and/or filaments travelling in the direction of advance in the form of a web, this method comprising at least one-step, called the prelooping step, in which the fibres and/or filaments individually undergo looping transversely to the direction of advance, if appropriate accompanied by transverse drawing.
As already mentioned above, transverse looping accompanied by drawing is carried out, for each individual fibre or filament, by means of rotary elements or looping discs which are spaced and arranged on a shaft transverse to the direction of advance of the web and between which looping fingers are arranged. This makes it possible to ensure that each fibre or filament is involved in at least one prelooping step and allows the parallelization of these elementary fibres and/or filaments.
The present method is characterized in that confinement of the material in the form of loops consisting of the particularly exactly parallelized fibres and/or filaments is carried out, and in that this confinement takes place directly on a support, without transport members, such as needles or transfer elements, being involved.
This confinement is obtained after a first transient step which is associated with the start-up of a product line and during which the first loops obtained by means of the step of prelooping the individual fibres and/or filaments form a stop in an arbitrary manner. The confinement takes the form of an accumulation of loops, which consist of parallelized fibres and/or filaments, one behind the other.
The successive loops are positioned essentially vertically by means of a detaching element which makes it possible to guide the material as far as the support, whilst at the same time holding the said material by means of a bar assembly.
The support may be directly the final substrate of the product to be produced and therefore consist of a fibre mat, a plastic film, a backing of the PVC type, etc.
If appropriate, instead of being deposited directly onto the substrate of the final product, the confined material could be gripped by an intermediate element, such as a spiked belt, a brush or a Velcro(copyright) support, the function of which is to maintain the crimped form of the loops while the free end of the material is being fixed to a substrate.
This fixing to the substrate is carried out by means of a glue, the viscosity of which is designed to make it possible to drive the individual fibres and/or filaments of the material, together with the substrate, whilst at the same time carrying out efficient adhesive bonding.
In general terms, it is possible to use either pastes or resins (acrylic, isocyanate, styrene-butadiene, phenolic, etc.) or thermoplastics in the form of a hot melt, film or powder (polyesters, polypropylene, EVA, PVC, etc.) or foams (PVC, acrylic, etc.), or direct adhesion by melting the verticalized fibre onto the substrate may be carried out. The means used for supplying the heat necessary for this purpose are preferably provided by an infrared furnace, a calender or a heating drum or else heating blades which take the form of plane metal parts comprising electrical resistors or ducts for the passage of heat-exchange fluids.
The speed of advance of the substrate may either be uniform or take place in bursts, in such a way that more marked confinement of the textile material on this support is obtained.